The markets for flame retardancy fibers have been huge and begun to pay attention to interior material for flame retardancy.
Synthetic fibers such as those formed of nylon, polyester, polypropylene and the like, because of being excellent in physical and chemical properties, find now wide applications in the form of clothing, curtain, carpet and other materials. However, these fibers are combustible; so they are required to have flame retardancy when applied to automotive trims, housing, etc.
Due to strong regulations in the field of fire service and environment, flame retardancy needs continuously become more demanding. In Japan, using flame retardancy fibers is legislated in infra-structures. In order to obtain approval, bed matrix, in particularly baby products, should be made of flame retardancy materials. Various products without eco-label could not enter into market throughout strict regulations of Europe.
In viewpoints of interior fiber materials for transportations (i.e., automotives, trains, ships, air transportations), flame retardant PET yarns (yarn contains flame retardancy agent in itself) or PET yarns performed by post flame retardancy finish have been employed in automotives. However, these do not meet required flame retardancy property and has a disadvantage of non friendly-environment. In trains, ships, air transportations, wool or acrylic fibers with excellent flame retardancy property have been adopted, and aramid fiber of high cost also adopted partly.
Whereas the interior materials for automotives only needs flammability (carbonization), those for trains, ships, and air transportations more require flammability (carbonization distance, glow time or LOI) as well as smoke density, toxic index. Therefore, it is very difficult for synthetic fibers such as PET, nylon and so forth to satisfy flame retardancy property, so that wool, acrylic fibers, or specialty fibers have been used
Like this, the requirement of interior materials suitable for transportations and additional functions has been increased. Some issues to be considered in functions of interior materials are security for fire, that is, flame retardancy property.
Imparting flame retardancy to fibers is generally achieved by adding flame retardants to the starting polymers or post-treating fibers with flame retardants.
One difficulty in securing stable flame retardancy property comes from the limitation of the amount of flame additives and restriction of halogen flame retardancy agent. Flame retardancy process (adding flame retardants during spinning step or post-treating finish with flame retardants) induces the endurance and emotional quality (design).
Particularly, since most of automotive interior materials are bonded with polyurethane foam, it is necessary that high flame retardancy materials such as polyphenylene sulfide (LOI is 34) with excellent flame retardancy is used so as to reinforce and supplement composite materials.
Recently, flame retardancy needs continuously become more demanding in the field of interior materials for house service or construction. For these use, polyester fibers have been widely used in that they are easily controlled and have price competitiveness. In spite of these advantages, they do not satisfy high flame retardancy property, for example, over 30 LOI.
In order to reduce damages resulted from fire, there is a necessity of flame retardancy fibers, and fibers capable of imparting thermal stability, chemical resistivity, and dimensional stability to interior materials, flame retardancy materials, and sound absorbing materials, which become high-volume market.
Typical example of the above fiber is polyphenylene sulfide. Since the polyphenylene sulfide fiber has inherently more stable with respect to heat. Thus, it offers many advantages of excellent flame retardancy property, stability with respect to smoke density, and controlling toxic gas. In addition, it has continuous thermal stability, chemical resistivity, low absorption, dimensional stability, and chemical resistance and so forth. Unlike this, PET by post flame retardancy finish or fibers added with flame retardancy agent has a limitation of flame retardancy property, poor smoke density, and is not capable of controlling toxic gas.
Polyphenylene sulfide fibers have been known that they can be dyed with disperse dye. However, they tends to be limited to the application of back-filter, electronic components, and automotive components without requiring dyeing.
For replacing conventional interior materials and engineering fabrics by improving dyeing and color fastness of polyphenylene sulfide, this encourages the development of polyphenylene sulfide. In other words, the thermal stability of polyphenylene sulfide (LOI is 34) is already verified, but securing verification of the smoke density and toxic gas and control technique is needed in order to combine interior materials for air transportation and interior materials.
Meanwhile, the most important property next to flame retardancy property is vision characteristic to be used in interior materials. For instance, because construction materials such as curtains and interior materials for movable means such as automotives are exposed to light under severe environment (sunlight or UV) for a long time, color fastness is important factor in dyed products.
Polyphenylene sulfide fibers have excellent flame retardancy, thermal stability, and chemical resistance but a weak to sunlight. Also there is a problem that its color is changed into brown when exposed to sunlight at a high temperature for a long time.
Accordingly, it has been proposed that fibers have flame retardancy property, thermal stability as well as excellent dyeing and color fastness and interior fabric using the same.